A SPICE model of multi-mode optical fiber in mid-channel link for package system SI transient simulations

In high-performance computer system design, optical links are applied to many system channels to replace traditional copper cables as mid-channel links. Multi-mode optical fiber is an important component in the mid-channel link. An accurate multi-mode fiber SPICE model is a key issue in the system signal integrity transient simulation as well as in generating IBIS-AMI optical link model. In this paper, a multi-mode fiber SPICE modeling method is proposed for graded-index core multi-mode fibers to include the signal integrity effects by modal dispersion, chromatic dispersion, attenuation, and even the total time flight. The proposed model can be used together with the VCSEL, photodiode, and trans-impedance amplifier SPICE models to simulate the mid-channel optical link using a general-purpose SPICE or SPICElike simulator which supports the I/O device transistor level models and other interconnect, packaging component SPICE models. Test cases on the 25Gb/s system eye diagram signal integrity simulation are shown using a graded-index multimode fiber.